The present invention concerns a supersonic nozzle, in particular for a turbojet engine.
Nozzles of this type are already known. They comprise essentially two annular systems, one of convergent flaps having their upstream edges hinged at the annular side of the duct outlet, the other of divergent flaps having their upstream edges hinged at the downstream edges of the convergent flaps. Drives, such as actuating cylinders are coupled, respectively, by transmission devices to at least some of the convergent flaps so as to cause them to pivot with respect to the edge of the duct in synchronism with each other. At the same time, the devices are designed to slave the positions of the divergent flaps with the positions of the convergent flaps. A device such as this makes it possible to continuously change the respective angles of the convergent flaps with respect to the nozzle axis, and to cause the angles of the divergent flaps to correspond with respect to the same axis in a positive manner. The designation "divergent flaps" does not exclude the possibility that under certain operating conditions the aforesaid flaps form the walls of a flow path with a constant section, or even with a convergent section. In fact, the two principal configurations of a supersonic nozzle such as this, and which were used when the nozzle was adapted for an aircraft turbojet engine, are, on the one hand the configuration corresponding to subsonic cruising speed, at which the divergent flaps are practically parallel to the axis of the nozzle, and, on the other hand, the configuration corresponding to the afterburner mode, permitting very high accelerations, and for which the divergent flaps are greatly tilted with respect to the axis of the nozzle.
In the majority of supersonic nozzles of known type, the devices used to transmit the control forces generated by the actuating drives, (generally actuating cylinders), comprise rods, connecting rods, levers, pivots, etc. These devices are distinct from the devices used to synchronize pivoting movement of the different convergent flaps, which generally comprise a ring concentric with the axis of the nozzle and coupled to the transmission devices mentioned. Devices of this type are described in French patents Nos. 72.42491, 74.08812, and 78.10546, for example.